Torque applying and torque limiting tool

ABSTRACT

A compact torque limiting unit to be turned by an ordinary hand or slow speed power wrench. It releases and spins freely when the limit for which it is set is reached. This prevents over torqueing. It comprises a cup shaped housing containing two clutch members, one rotatable in and fluid supported for longitudinal movement in said housing and the other rotatable in the housing and having an outwardly opening socket to receive a driving part of a conventional wrench. The two clutch members are connected with each other by interengaging means which transmits torque and releases for free running when a maximum torque for which the tool is set is reached. The housing has an external shank to receive a wrench socket by which a threaded part can be turned. The housing has in it a self contained, adjustable, valve controlled fluid circulation system which includes fluid storage cavities and controls release of the two clutch members for free running.

United States Patent [191 [111 3,799,307 Tate Mar. 26, 1974 TORQUEAPPLYING AND TORQUE LIMITING TOOL lnventorz Harry R. Tate, 3131 DyesInlet Rd., Bremerton, Wash. 98310 Filed: Jan. 29, 1973 Appl. No.:327,826

[52] US. Cl. 192/56 F, 192/59, 81/52.4 R

[51] Int. Cl. Fl6d 43/20 [58] Field of Search 192/56 F, 59; 81/524 R,81/524 A [56] References Cited UNITED STATES PATENTS 2,408,501 10/1946Wright 192/56 F 3,608,334 9/1971 Zinner 192/56 F 3,664,474 5/1972 Blakeet al. 192/56 F Primary ExaminerAllan D. Herrmann [5 7 ABSTRACT Acompact torque limiting unit to be turned by an ordinary hand or slowspeed power wrench. it releases and spins freely when the limit forwhich it is set is reached. This prevents over torqueing. It comprises acup shaped housing containing two clutch members, one rotatable in andfluid supported for longitudinal movement in said housing and the otherrotatable in the housing and having an outwardly opening socket toreceive a driving part of a conventional wrench. The two clutch membersare connected with each other by interengaging means which transmitstorque and releases for free running when a maximum torque for which thetool is set is reached. The housing has an external shank to receive awrench socket by which a threaded part can be turned. The housing has init a self contained, adjustable, valve controlled fluid circulationsystem which includes fluid storage cavities and controls release of thetwo clutch members for free running.

7 Claims, 6 Drawing Figures I ll L-? I [i 23 1. ll Ii /0 2 ,7 l i l ,5/ZdP x450 57 P-zo 49 Zr: y ,T 9 ff 0 27 1 I 32 32 14 2 i l /4 TORQUEAPPLYING AND TORQUE LIMITING TOOL SUMMARY OF THE INVENTION Conventionaltorque wrenches are usually large cumbersome devices complete withhandles or other driving means and they usually have means to sound ordisplay a signal when the torque for which they are set is reached. Thisdoes not prevent the user from applying more torque after the signal isgiven.

An object of-this invention is to provide a simple, reliable, compactand efficient torque tool which can be set for any desired torque withinchosen limits and will release and spin freely when the limit for whichit is set is reached thus making it impossible for the user to applytorque in excess of the chosen limit.

Another object is to provide a torque wrench head or cell or unit whichis externally smooth and is light in weight, making it convenient tocarry in an ordinary tool kit and one which does not have any handle butcan be turned or driven by the handle or driving part of any handoperated socket wrench or the driving part of any slow speed powerwrench of proper size.

Another object is to provide a releasable torque wrench head or cell inwhich release or free spinning of the wrench is responsive to variationsin fluid pressure but which is self contained and free from externalconnections with fluid conduits and other fluid pressurizing andcontrolling devices.

Another object is to provide a torque wrench head or cell comprising acup shaped housing having, in its bottom end, fluid storage cavities andhaving in it a ram clutch member which is rotatable with it andlongitudinally movable in it and forms one wall of a fluid pressurechamber, and also having in it rotatively supported driving clutchmember adapted to receive the driving part of an ordinary square-drivewrench, said two clutch members having between their two opposed sides,interengaging means, which can be cams, and which will transmit torqueand will be automatically disengaged by the escape of fluid from saidfluid pressure chamber into said fluid storage cavities when torquegenerated pressure of the fluid in said chamber reaches a predeterminedamount for which the wrench head or cell is set and said wrench headfurtherhaving means for returning fluid from the cavities to thepressure chamber when the wrench is free from torque.

Other objects of the invention will be apparent from the followingdescription and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view in elevation of atorque wrench head or cell embodying my invention.

FIG. '2 is an axial sectional view, with parts in elevation, of thesame.

FIG. 6 is a detached perspective view of a rotatively adjustable torqueindicator ring used on the housing of my wrench head or cell.

Like reference numerals refer to like parts throughout the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT This torque wrench head or cellcomprises four main parts, namely, a cup shaped housing '10, a ramclutch member 11 and a driving clutch member 12, both disposed withinthe housing l0, and a cap 13 adapted to be removably threaded onto theupper end of the housing 10,and cooperating therewith in containing andsupporting clutch members 11 and 12. Ram clutch member 11 has in it anaxial bleeder opening which is normally closed by a screw plug 9. Theinside wall of the housing 10 is cylindrical and dimensioned to providechambers of different diameters with shoulders between them, as shown inFIG. 2. The bottom wall 14 of housing 10 is relatively thick and isprovided with an external axial shank 8, preferably of square crosssection to adapt it to fit within the socket of a conventional squaredrive socket wrench. This device thus functions as a torque head or cellby which an ordinary socket wrench can be converted into a torquelimiting wrench.

The upper end portion of the driving clutch member 12 is cylindrical androtatively supported in a suitable bearing in the cap 13 and it has anupwardly opening socket 15 of square cross sectional shape to receivethe driving part of a hand operated or a slow speed power operatedsocket wrench. An external annular flange 16 is provided on the lowerend of the driving clutch 12 and a narrow internal shoulder 17 in thewall of housing member 10 limits downward movement of said drivingclutch 12. Ball type thrust bearings 18 are provided between flange 16and an overhanging part of the cap 13. A plurality of downwardlyextending members 19, herein termed cams, are integral with the lowerface of the driving clutch 12. These cams 19 are of generally triangularshape and have inclined or beveled side walls 20. The cams 19 on drivingclutch member 12 are adapted to fit between and react against similarearns 21 on the upper face of the ram clutch member 11. Cams 21 haveinclined side walls 22 which contact and react against inclined sidewalls 20 of cams 19.

The upper peripheral end portion of ram clutch member 11 is providedwith outwardly protruding, spaced apart tooth like members 23 which mateand interfit with spaced apart longitudinally extending ribs or splines24 on the inner wall of housing 10. The meshing teeth 23 and splines 24compel the ram clutch member 11 to rotate with housing 10 while allowingit to move longitudinally in said housing. The lower end part of ramclutch member 11 is cylindrical and fits snugly within a cylindricalpart of the housing 10 and an O-ring 25 is provided in a suitable groovenear the lower end of said cylindrical part of member 11 to serve as afluid seal. This forms a fluid pressure chamber 26 between the housingbottom 14 and the ram clutch member 11.

The bottom wall 14 has in it two transverse, intersecting bores orpassageways 28, FIG. 2 and 33, FIG. 3, which serve as fluid storagecavities and said bottom wall 14 further has in it an axial bore 27which connects the pressure chamber 26 with the fluid storage cavities28 and 33. A spring pressed valve 29 is disposed in a suitable housing41 which is threaded into the upper end of bore 27. The check valve 29is adapted to permit fluid to flow from cavities 28 and 33 into chamber26 but to prevent a reverse flow of such fluid. Two pistons 31 ofduplicate construction are provided in the bore or passageway 28 atopposite sides of the axial position where bore 28 intersects bore 27. Apush rod 32 is rigid with each piston 31 and extends outwardly through afitting 32' to the exterior of housing 10. Rods 32 are used to manuallymove the pistons 31 inwardly.

An adjustable, pressure responsive valve 34 in the cavity 33 is urged bya spring 35 against a valve seat 36 in said cavity. A screw plug 37,spaced outwardly from valve seat 36, closes the end of the cavity 33shown at the left in FIG. 3. A fluid pressure relief passageway 38extends between fluid pressure chamber 26 and a part of the cavity 33adjacent plug 37 and at the side of the valve seat 36 opposite the valve34.

When ram clutch 11 is moved so as to reduce the volume of chamber 26fluid will be caused to flow through passageway 36 into a part of cavity33 between valve 34 and plug 37, thence past valve 34 into a part ofcavity 33 which communicates with a part of the cavity 28 betweenpistons 31. This will move said pistons apart and cause said rods 32 toprotrude outwardly from opposite sides of the housing 10. When theclutch members 11 and 12 are free from torque and the pistons 31 arethus spread apart ram clutch 11 can be moved toward and into meshingrelation with driving clutch 12 by exerting a squeezing pressure on saidrods 32.

The end of spring 35 remote from valve 34 rests against a nut 39 whichis threaded within passageway 33 and can be turned by an adjustingspindle 40 to vary the pressure of said spring 35 against valve 34. Boththe spindle 40 and the hole in the nut 39 through which said spindle 40passes are preferably square so the nut is rotatable with and movablelengthwise of the spindle. Spindle 40 has on its outer end a rigidlyattached coaxial hub 42 which fits snugly and rotatively within the bore33 and is grooved to receive an O-ring 43 for fluid sealing purposes.The hub 42 is secured against longitudinal movement in bore 33 by ascrew 44, the inner end I of which extends into an annular groove 45 insaid hub.

A head 46 rigid with the outer end of hub 42 is adapted to receive ascrew driver or like tool by which the spindle 40 can be turned to movethe unit 39 lengthwise in the bore 33 and adjust the pressure of thespring 35 against the valve 34. The periphery of the head 45 is providedwith gear teeth 48 which mesh with other gear teeth 49 on the edge of atwo piece mounting ring which is composed of two similar semi-circularparts 50 and is adapted to fit rotatively within an annular groove onthe exterior of the housing 10. A circular split ring 51 of thinresilient material is adapted to be snapped over the two piece mountingring 50. The split ring 51 fits snugly around the two piece mountingring 50 and is secured thereto by screws or other devices appliedthrough perforations 52, FIG. 6, in the split ring. This provides a ringassembly which can be readily applied to housing 10. The split ring 51and housing are provided with graduations, preferably expressed in footpounds, which can be set relative to each other by the turning ofspindle 40 which simultaneously adjusts the pressure of spring 35against valve 34.

To fill or charge the tool with hydraulic fluid, which can be SAE 20oil, the tool is preferably held upright by securing the shank 8 in avise, the tiller plug 37 is removed and an ordinary oil pump is appliedto the filler plug opening and the oil forced into the tool. The oilwill fill passageway 38 and chamber 26 and will move the ram clutchmember 11 upwardly as far as possible into fully meshed relation withthe driving clutch member 12. At this time the oil pressure will notusually be high enough to cause the oil to open and flow past valve 34.After chamber 26 has been filled the driving clutch is turned until itruns free to force ram clutch 12 down and force the oil past valve 34into cavities 28 and 33, the oil pump being constructed so the oil cannot be forced back into it. This procedure is repeated, if necessary,until the two pistons 31 stand at about the limit of their outwardmovement or until there is enough oil in the cavities 28 and 33 so thatwhen the pistons 31 are moved from their outermost to their innermostpositions they will always displace enough oil to move the ram clutchmember 11 into fully meshed relation with driving clutch member 12. Whenoil is introduced into the tool, as just hereinbefore described most ofthe trapped air will be in the upper part of chamber 26 and this air canbe evacuated by removing the bleeder plug 9 from the ram clutch member11 and manipulating the piston rode 32 so as to bubble it out throughthe bleeder plug opening.

This tool can be used to apply either right or left torque to variousdifferent threaded fastening devices to which shank 8 can be connectedby an ordinary wrench socket. Before applying the tool to a part onwhich a predetermined torque is to be exerted a squeezing pressure isapplied to the piston rods 32 and the pistons 31 are caused to displaceenough oil from the oil storage cavities past check valve 29 intochamber 26 to move the ram clutch member 11 upwardly until the earns 21are in fully meshed engagement with the cams 19 on driving clutch 12.The earns 19 and 21 serve as interengaging means which will transmittorque between clutch members 11 and 12 and at the same time will exertend thrust which bears a constant relation to the torque and which tendsto move the two clutch members apart and will disengage them at thelimit for which the indicator ring 51 is set.

I claim:

1. Torque wrench means comprising a cup shaped housing having a closedend provided with fluid storage cavities and an external shank; a drivenram clutch member fitting snugly within said housing, said ram clutchmember being longitudinally movable within said housing and rotatablewith said housing and cooperating with the housing in forming a fluidpressure chamber between it and the bottom of said housing; a drivingclutch member rotatively supported in the upper end portion of saidhousing and having in it a socket shaped and dimensioned fornon-rotatable connection with a driven part; interengageable devicesprovided between adjacent sides of said two clutch members operable intransmitting torque between said clutch members and responsive to torquein moving said clutch members apart and disengaging them from eachother; fluid passageways in said housing extending between said fluidpressure chamber and said fluid storage cavities; an adjustable springpressed check valve in said passageways providing for a flow of fluidunder torque generated pressure from said chamber to said fluid storagecavities; another check valve in said passageways providing for a flowof fluid from said cavities to said chamber; and fluid displacementmeans connected with said cavities between said two valves and operablefrom the exterior of said housing for displacing fluid from saidcavities past said other check valve into said chamber in the absence oftorque generated pressure in the fluid therein.

2. The torque wrench means as claimed in claim 1 in which the fluiddisplacement means includes two opposed pistons reciprocable in thefluid storage cavities in the housing and provided respectively with twopiston rods which extend in opposite directions from the pistons andprotrude from the housing.

3. The torque wrench means as claimed in claim 1 in which theinterengageable devices between the two clutch members are cams rigidwith the clutch members and shaped and dimensioned to mesh with eachother and having contacting side surfaces which are convergentlyinclined from the clutch members outwardly.

4. The torque wrench as claimed in claim 1 in which adjusting devicesreadily accesable from the exterior of the housing are operativelyconnected with said adjustable spring pressed check valve.

5. The torque wrench as claimed in claim 1 in which adjusting devicesreadily accesable from the exterior of the housing are operativelyconnected with said adjustable spring pressed check valve and in whichpressure indicating means is movably supported on the exterior of saidhousing and operatively connected with said adjusting devices.

6. The torque wrench as claimed in claim 1 in which the bottom of thehosuing is of substantial thickness and in which a major portion of thefluid cavity spaces therein are formed by two transverse intersectingbores positioned at a substantial angle relative to each other.

in the other bore.

1. Torque wrench means comprising a cup shaped housing having a closedend provided with fluid storage cavities and an external shank; a drivenram clutch member fitting snugly within said housing, said ram clutchmember being longitudinally movable within said housing and rotatablewith said housing and cooperating with the housing in forming a fluidpressure chamber between it and the bottom of said housing; a drivingclutch member rotatively supported in the upper end portion of saidhousing and having in it a socket shaped and dimensioned fornonrotatable connection with a driven part; interengageable devicesprovided between adjacent sides of said two clutch members operable intransmitting torque between said clutch members and responsive to torquein moving said clutch members apart and disengaging them from eachother; fluid passageways in said housing extending between said fluidpressure chamber and said fluid storage cavities; an adjustable springpressed check valve in said passageways providing for a flow of fluidunder torque generated pressure from said chamber to said fluid storagecavities; another check valve in said passageways providing for a flowof fluid from said cavities to said chamber; and fluid displacementmeans connected with said cavities between said two valves and operablefrom the exterior of said housing for displacing fluid from saidcavities past said other check valve into said chamber in the absence oftorque generated pressure in the fluid therein.
 2. The torque wrenchmeans as claimed in claim 1 in which the fluid displacement meansincludes two opposed pistons reciprocable in the fluid storage cavitiesin the housing and provided respectively with two piston rods whichextend in opposite directions from the pistons and protrude from thehousing.
 3. The torque wrench means as claimed in claim 1 in which theinterengageable devices between the two clutch members are cams rigidwith the clutch members and shaped and dimensioned to mesh with eachother and having contacting side surfaces which are convergentlyinclined from the clutch members outwardly.
 4. The torque wrench asclaimed in claim 1 in which adjusting devices readily accesable from theexterior of the housing are operatively connected with said adjustablespring pressed check valve.
 5. The torque wrench as cLaimed in claim 1in which adjusting devices readily accesable from the exterior of thehousing are operatively connected with said adjustable spring pressedcheck valve and in which pressure indicating means is movably supportedon the exterior of said housing and operatively connected with saidadjusting devices.
 6. The torque wrench as claimed in claim 1 in whichthe bottom of the hosuing is of substantial thickness and in which amajor portion of the fluid cavity spaces therein are formed by twotransverse intersecting bores positioned at a substantial angle relativeto each other.
 7. The torque wrench as claimed in claim 1 in which thebottom of the housing is of substantial thickness and in which a majorportion of the fluid cavity space therein is formed by two transverseintersecting bores positioned at a substantial angle relative to eachother and in which the fluid displacement means is disposed in one ofsaid bores and the adjustable spring pressed valve and adjusting meansfor said valve are disposed in the other bore.